Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors: Implications for Potential Vapor Intrusion Hazards Roger Brewer & Lynn Bailey Hazard Evaluation and Emergency Response Hawai‘i Department of Health April

There are three methods to gain knowledge: The first, reflection, is the noblest; The second, imitation, is the easiest; And the third, experience, is the bitterest. Confucius

Reference: Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors, Implications for Potential Vapor Intrusion Hazards: Hawai’i Department of Health, Hazard Evaluation and Emergency Response, 3 Note: Significant vapor intrusion problems have not been identified for existing buildings at any of the study sites included in this presentation. The site data are presented for example only.

Acknowledgements Field study funded under a grant from USEPA Region IX; Hickam AFB/NAVFAC Hawai’i past work and field assistance Field work carried out by HDOH HEER & UST staff with assistance by several local consultants; Numerous consultations with regulators and consultants on the mainland. 4

HDOH Petroleum Vapor Intrusion Guidance HEER EHE guidance (2005; last updated Fall, 2011) HEER Technical Guidance Manual (Section 9); Test for TPH plus BTEXN and methane in soil gas; TPH soil gas action levels: 2005: Residential = 26,000 ug/m 3 (based on limited, published information); 2011: Residential = 130,000+ ug/m 3 (based on this study). 5

Vapor Intrusion Indoor Air Action Level vapor diluted Slab or crawl space contaminated soil or groundwater diffusion to slab base advective flow into building Subslab Soil Gas Action Level Soil Gas AL res = 1,000 x Indoor Air AL Soil Gas AL C/I = 2,000 x Indoor Air AL 6

Do We Really Need to Worry About TPH? How can something that smells so bad or can catch on fire pass a “risk assessment”? 7

Key Questions… 1.Are BTEXN and especially benzene in soil gas adequate to screen for potential vapor intrusion hazards at petroleum-contaminated sites? 2. Could TPH still pose a vapor intrusion risk even though BTEXN meet acceptable risks? a. What is the toxicity of TPH in petroleum vapors? b. What is carbon range makeup of vapor-phase TPH? 8

Gasolines Diesel Fuels Fuel Oils Fuels and Carbon Ranges C2 C4 C6 C8 C12 C16C20C24 C28 C32 C36 69'C 126'C216'C343'C402'C449'C C0 BTEXPAHsMethane Volatile/Semi-Volatile 9

Toxicity of Total Petroleum Hydrocarbons TPH Working Group (mid/late 1990s) Subsequent Guidance Massachusetts DEP (1997+) Washington DOE (2006) California EPA (DTSC 2009) USEPA (2009) 10

Massachusetts DEP TPH Carbon Ranges C5-8C9-12 C11-22 C19-36C13-18 Potential Vapor Phase C2 C4 C6 C8 C12 C16C20C24 C28C32C36 C0 C9 -10 Aliphatics Aromatics Gasolines Diesel Fuels Fuel Oils TPH = Sum of Aromatics + Aliphatics (excluding BTEXN, etc.) 11

C2 C4 C6 C8 C12 C16C20C24 C28 C32 C36 C0 Vapor-Phase Carbon Ranges C5-8C9-18 C9-16 Less Toxic Gasolines Diesel Fuels Fuel Oils More Toxic TPH = Sum of Aromatics + Aliphatics (excluding BTEXN, etc.) 12 Aliphatics Aromatics

Carbon Ranges - Vapor Sample Collection Volatile Petroleum Hydrocarbons (VPH): C5-C8 Aliphatics C9-C12 Aliphatics C9-C10 Aromatics Extractable Petroleum Hydrocarbons (EPH): C13-C16 Aliphatics C11-C16 Aromatics VPH Compounds: Summa canisters OK EPH Compounds: Sorbent tubes required 13

TPH Carbon Range Action Levels Carbon Range RfC (ug/m 3 ) Residential Indoor Air (ug/m 3 ) Residential Soil Gas (ug/m 3 ) C5-8 aliphatics ,000 C9-18 aliphatics ,000 C9-16 aromatics ,000 USEPA 2009 Reference Concentrations Target Hazard Quotient = 1.0 Assumes indoor air:subslab soil gas Attenuation Factor of Odor Threshold (ug/m 3 ) approximately 1,000 ug/m 3 Use same as action levels for BTEXN and other individual VOCs 14

TPH Mixtures: Weighted Toxicity & Action Levels Weighted TPH RfC= 216 ug/m 3 TPH Indoor Air res = 250 ug/m 3 TPH Soil Gas res = 250,000 ug/m 3 Weighted TPH RfC (ug/m 3 ) = C9-C18 Aliphatics C5-C8 Aliphatics C9-C16 Aromatics 15

Critical TPH:Target Compound Ratios Point where relative proportion of “less toxic” vapor-phase TPH will overwhelm “more toxic” individual compounds Critical TPH Ratio = Least Stringent TPH Action Level Most Stringent Target Compound Action Level Critical TPH:Benzene Ratio = 630 ug/m 3 (C5-C8 aliphatics) 0.31 ug/m 3 (10 -6 cancer risk) Critical TPH:Benzene Ratio = 2,032 TPH will always drive vapor intrusion risk if the TPH:Benzene ratio exceeds 2,032:1 Useful as initial screening tool to evaluate potential vapor intrusion risk drivers 16

TPH:Benzene Soil Gas RatioRisk Driver >2,032 TPH will always drive vapor intrusion risk (TPH HQ >1.0 when benzene ECR <10 -6 ) 3 to 2,032 TPH could drive vapor intrusion hazards (depends on carbon range makeup and target benzene risk) <3 Benzene will always drive vapor intrusion risk. (TPH HQ <1.0 when benzene ECR <10 -4 ) TPH vs Benzene in Vapor Intrusion Risk Notes High: Ratio of least stringent TPH action level to most stringent benzene action level. Low: Ratio of least stringent TPH action level to most stringent benzene action level. 17

TPH Will Always Drive VI Risk if… VOC Indoor Air Action Level (ug/m 3 ) Critical TPH Ratio Naphthalene0.0728,750 1-Methylnaphthalene0.292,172 Benzene0.312,032 Ethylbenzene Xylenes2130 Toluene1, Based on least conservative TPH action level (630 ug/m 3 ) and most conservative VOC action level (e.g., cancer risk and HQ 1.0). TPH could drive vapor intrusion risk below these ratios depending on carbon range makeup and target risk applied to the individual VOC. 18

Off To The Field! Key sites for collection of soil gas samples identified; Two phases of sampling: Phase I: Summas, TO-15 & MA-APH Phase II: Summas+Sorbent Tubes, TO-3, TO- 15, TO-17 & MA-APH 19

TO-15 TO-17 Sorbent Tube Range Summas or Sorbent Tubes for Soil Gas? (Summas will miss heavier VOCs) C2 C4 C6 C8 C12 C16C20C24 C28 C32 C36 C0 Summa Range (Hayes 2007) Larger volume Familiarity Limited to C12 SummasSorbent Tubes Up to C24+ Small volume (50ml) Saturation limitation Less familiar 20

Key Study Sites Site D Site A Site B Site E Site C 21

Sample Collection Summa Canisters (1liter summas) Sorbent Tubes (60 ml syringes) 22 Max Draw = 50ml Two Tubes to Evaluate Breakthrough

Results of Field Data Following summaries based on Summa canister data Sorbent tube data very similar to Summa data Minimal VOCs greater than C12 in soil gas Naphthalene was usually ND and not a significant risk driver in comparison to TPH (or benzene) TEX likewise not significant risk drivers 23

TPH Dominates BTEXN in Vapors (BTEXN component decreases in aged releases?) Site/Fuel Type Average Soil Gas Composition (TO-15 Data) TPH*BTEXNTPH:Benzene Gasoline (Fresh Vapors)91.6%8.4%170 Diesel (Fresh Vapors)93.7%6.3%206 JP-8 (Fresh Vapors)96.4%3.6%301 Site A (JP-4/AVGAS?) 99.6%0.4%1,513 Site B (mixed fuels) 99.5%0.5%4,174 Site C (JP-8 +/- JP-4) 99.7%0.3%18,710 Site D (MOGAS/JP-4/AVGAS) 98.3%1.7%9,135 Site E (diesel) 99.9%0.1%18,611 *Exhaust samples 30-40% BTEXN 24

TO-15 Gas Chromatograph Fresh Gasoline Vapors C5-C8 Benzene C5C9 C9-12 Naphthalene C13 25

Weighted RfC= 565 ug/m 3 Indoor Air res = 590 ug/m 3 Soil Gas res = 590,000 ug/m 3 TPH:Benzene = 170 Carbon Range Chemistry and Weighted TPH Toxicity Fresh Gasoline Vapors Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics

Who’s Driving…? TPH vs Benzene as VI Risk Driver Calculate equivalent TPH concentration for sample/site at target benzene action level based on TPH:Benzene ratio Divide by weighted site-specific TPH action level Gasoline Vapor Example (using indoor air action levels): Target Benzene Action Level = 0.31 ug/m 3 (10 -6 risk) TPH:Benzene = 170:1 Equivalent TPH = 53 ug/m 3 Weighted TPH Action Level = 590 ug/m 3 TPH noncancer HQ = 53/590 = 0.1 Benzene drives vapor intrusion risk (TPH HQ <1.0 when benzene risk = ) 27

Benzene TPH Hazard Quotient TPH vs Benzene Vapor Intrusion Risk Fresh Gasoline Vapors Benzene Cancer Risk Benzene adequate to evaluate vapor intrusion provided that a target cancer risk is used. (TPH noncancer HQ still <1 when benzene risk ) TPH HQ=0.1 Based on TO-15 Summa Data 28

TO-15 Gas Chromatograph Fresh Diesel Vapors C5-C8C9-12 Benzene Naphthalene C5C9C13 29

Weighted RfC= 216 ug/m 3 Indoor Air res = 250 ug/m 3 Soil Gas res = 250,000 ug/m 3 TPH:Benzene = 206 Carbon Range Chemistry and Weighted TPH Toxicity Fresh Diesel Vapors Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 30

Based on TO-15 Summa Data 31 TPH Benzene HQ=0.3 TPH vs Benzene Vapor Intrusion Risk Fresh Diesel Vapors TPH Hazard Quotient Benzene Cancer Risk Benzene adequate to evaluate vapor intrusion provided that a target cancer risk is used. (TPH noncancer HQ still <1 when benzene risk )

Gas Chromatograph Fresh JP-8 Vapors C5-C8 Benzene C5 C9-12 Naphthalene C13 C9 32

Weighted RfC= 225 ug/m 3 Indoor Air res = 230 ug/m 3 Soil Gas res = 230,000 ug/m 3 TPH:Benzene = 301 Carbon Range Chemistry and Weighted TPH Toxicity Fresh JP-8 Vapors Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 33

TPH Benzene HQ=0.4 TPH vs Benzene Vapor Intrusion Risk Fresh JP-8 Vapors TPH Hazard Quotient Benzene Cancer Risk Benzene adequate to evaluate vapor intrusion hazards provided that a target cancer risk is used. (TPH noncancer HQ<1 when benzene risk ) Based on TO-15 Summa Data 34

Gas Chromatograph Site A (AVGAS) C5-C8 Benzene C5C9 C9-12 Naphthalene C13 35

Weighted RfC= 510 ug/m 3 Indoor Air res = 530 ug/m 3 Soil Gas res = 530,000 ug/m 3 TPH:Benzene = 1,513! (reduced benzene in soil gas) Carbon Range Chemistry and Weighted TPH Toxicity Site A (AVGAS) Average TPH in Soil Gas 71,000,000 ug/m 3 Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 36

TPH Benzene HQ=0.9 TPH vs Benzene Vapor Intrusion Risk Site A (AVGAS) TPH Hazard Quotient Benzene Cancer Risk Benzene adequate to evaluate vapor intrusion hazards provided that a target cancer risk is used. (TPH noncancer HQ<1 when benzene risk ) Based on TO-15 Summa Data 37

Chemical/ Carbon Range *Henry’s Constant Benzene 0.23 Ethylbenzene 0.32 Toluene 0.27 Xylenes 0.29 Naphthalene C9-C10 Aromatics 0.33 C11-C22 Aromatics 0.03 C5-C8 Aliphatics 54 C9-C12 Aliphatics 65 C9-C18 Aliphatics 69 C19-C36 Aliphatics 110 Where’s the BTEXN? Partitioning of Compounds in Soil *Theoretical ratio of vapor-phase mass to dissolved-phase mass at equilibrium. Dissolved-phase dominates if H’ <1.0. Aromatics Prefer to be in the Water Aliphatics Prefer to be in the Vapors 38

Gas Chromatograph Site B (Mixed Fuels) C5-C8 Benzene C5C9 C9-12 Naphthalene C13 39

Weighted RfC= 443 ug/m 3 Indoor Air res = 460 ug/m 3 Soil Gas res = 460,000 ug/m 3 TPH:Benzene = 4,174! (reduced benzene in soil gas) Carbon Range Chemistry and Weighted TPH Toxicity Site B (Mixed fuels) Average TPH in Soil Gas 44,000,000 ug/m 3 Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 40

TPH Benzene HQ=2.8 TPH vs Benzene Vapor Intrusion Risk Site B (Mixed Fuels) TPH Hazard Quotient Benzene Cancer Risk TPH always drives potential vapor intrusion hazards. (TPH noncancer HQ>1 even when benzene risk ) Based on TO-15 Summa Data 41

Gas Chromatograph Site C (JP-8 +/- J-4) C5-C8 Benzene C5C9 C9-12 Naphthalene C13 42

Weighted RfC= 251 ug/m 3 Indoor Air res = 260 ug/m 3 Soil Gas res = 260,000 ug/m 3 TPH:Benzene = 18,710!! (minimal benzene in soil gas) Carbon Range Chemistry and Weighted TPH Site C (JP-8 +/- JP-4) Average TPH in Soil Gas 17,000,000 ug/m 3 Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 43

TPH Benzene HQ=22 TPH vs Benzene Vapor Intrusion Risk Site C (JP-8 +/- J-4) TPH Hazard Quotient Benzene Cancer Risk TPH always drives potential vapor intrusion hazards. (TPH noncancer HQ>1 even when benzene risk ) Based on TO-15 Summa Data 44

TO-15 Gas Chromatograph Site D (JP-4) C5-C8 Benzene C5C9 C9-12 Naphthalene C13 45

Weighted RfC= 211 ug/m 3 Indoor Air res = 220 ug/m 3 Soil Gas res = 220,000 ug/m 3 TPH:Benzene = 9,135! (minimal benzene in soil gas) Carbon Range Chemistry and Weighted TPH Site D (JP-4) Average TPH in Soil Gas 630,000 ug/m 3 Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 46

TPH Benzene HQ=13 TPH vs Benzene Vapor Intrusion Risk Site D (JP-4) TPH Hazard Quotient Benzene Cancer Risk TPH always drives potential vapor intrusion hazards. (TPH noncancer HQ>1 even when benzene risk ) Based on TO-15 Summa Data 47

Gas Chromatograph Site E (Diesel) C5-C8 Benzene C5C9 C9-12 Naphthalene C13 48

Weighted RfC= 127 ug/m 3 Indoor Air res = 130 ug/m 3 Soil Gas res = 130,000 ug/m 3 TPH:Benzene = 18,600!! (minimal benzene in soil gas) Carbon Range Chemistry and Weighted TPH Site E (Diesel) Average TPH in Soil Gas 2,900,000 ug/m 3 *Reference site for default TPH RfC in Fall 2011 TPH soil gas action levels. Based on TO-15 Summa Data C9-C12 Aliphatics C5-C8 Aliphatics C9-C10 Aromatics 49

TPH Benzene HQ=44 TPH vs Benzene Vapor Intrusion Risk Site E (Diesel) TPH Hazard Quotient Benzene Cancer Risk TPH always drives potential vapor intrusion hazards. (TPH noncancer HQ>1 even when benzene risk ) Based on TO-15 Summa Data 50

TPH vs Benzene as Vapor Intrusion Risk Site/Fuel Type Vapor Intrusion Risk Driver TPH Drives Risk *Benzene Drives Risk Gasoline (Fresh Vapors) X Diesel (Fresh Vapors) X JP-8 (Fresh Vapors) X Site A (JP-4/AVGAS?) XX Site B (mixed fuels) X Site C (JP-8 +/- JP-4) X Site D (MOGAS/JP-4/AVGAS) X Site E (diesel) X *Assuming a target, cancer risk is used for benzene. 51

Other Sites TPH vs BTEXN Site/Fuel Type TPH:Benzene In Soil Gas HAFB SS156-E (gasolines)244 to 1,296 ConocoPhillips (mixed)97 to 5,400 Lipoa Place (mixed)82 to >6,400 Challenger Loop (JP-4, JP-8)2,800 to 5,100 Aloha Petroleum (gasolines)366 to 13,100 HAFB SS156-J (mixed)560 to 165,000 HAFB CG110 (diesels)1,600,000 TPH:Benzene ratio highly variable Best to always test for TPH 52

Back to the Key Questions… Q: What is TPH in petroleum vapors made of? Answers: Mostly C5-C8 aliphatics, with an increased proportion of C9+ aliphatics in middle distillate (diesel, etc.) vapors. Aromatics, including BTEXN, make up a very minor component of vapors, especially at aged release sites. 53

Key Questions… Q:What is the toxicity (RfC) of TPH in petroleum vapors? Answer: Inhalation Reference Concentration for TPH will range from 100 ug/m 3 and 600 ug/m 3 (based on USEPA 2009 guidance). Vapors from gasolines will be closer to 600 ug/m 3. (dominance of C5-C8 aliphatics) Vapors from middle distillates will be closer to 100 ug/m 3 (presence of C9-C12 aliphatics) TPH Indoor air action levels similar to TPH RfC 54

Key Questions… Q:Are BTEXN and especially benzene in soil gas adequate to screen for potential vapor intrusion risks? Answers (more studies needed): Yes – But only for gasoline-contaminated sites and only if a conservative target risk is used (e.g., ); Aromatics can be preferentially removed from vapors via partitioning into moisture and degradation (but aliphatics will also be degraded); Reliance on benzene only can miss significant vapor intrusion hazards at diesel/middle distillate sites; TX not present in significant enough amounts to drive vapor intrusion risks at the study sites (ethylbenzene?); Naphthalene not detected in most soil gas samples and not a reliable indicator of vapor intrusion risk. 55

Key Questions… Q: Can TPH still pose a vapor intrusion risk even though BTEXN meet acceptable risks? Answers: Yes - TPH drives vapor intrusion risk over BTEXN at four of the five sites tested; TPH data especially important at sites with middle distillates (but vapor emission rates will be lower compared to gasolines); TPH alone would have been adequate to screen all of the study sites for potential vapor intrusion hazards (i.e., take care of the TPH and you will take care of the benzene). 56

Already Here & Coming Soon Study data used to update HEER TPH soil gas action levels (based on Fishing Village data); Draft report to be posted in March; Final report to be posted this spring; Methylnaphthalenes? (not significant in this study); Updated TPH Carbon Range guidance and soil gas sample collection guidance to be posted this summer; Comments and ideas always welcome. Now we know what the source area looks like… 57

RfCs AFs Biodegradation TPH Carbon Ranges Don’t Panic! BTEXN Subslab Vapor Intrusion Next Step: Pre-Screening Sites for Potential Vapor Intrusion Concerns 58

Avoid Setting The Site Screening Bar Too Low When do we need to look more closely (screening levels)? When is remediation really required (high risk sites)? Risk Pyramid of Investigated Sites Site Screening Bar High Risk Remedial Action Ultimately Required (don’t miss) Medium Risk Flagged in Screening but No Action Ultimately Required (minimize) Low Risk Eliminated During Screening, No Further Action Required (maximize) 59

Avoid Setting The Site Screening Bar Too High Risk Pyramid of Investigated Sites Site Screening Bar High Risk Remedial Action Ultimately Required (don’t miss) Medium Risk Flagged in Screening but No Action Ultimately Required (minimize) Low Risk Eliminated During Screening, No Further Action Required (maximize) 60

Screening Sites for Further Investigation Let’s Be Rational...: Don’t over compound conservative screening assumptions (e.g., “Tomb Model” for IA:SG attenuation and target risk); Biodegradation and attenuation away from source area; Distance from source area; De minimis volumes of contaminated soil and areas of free product (regardless of concentrations); Other considerations: -Alternative toxicity factors; -Target risks vs typical background; -Tidal pumping &subslab oxygenation -Explosion, odor concerns (including methane); -Focus on subslab data. Avoid testing indoor air (too many indoor & outdoor sources) Balance uncertainty about benefit to human health with certainty about economic impact on property owners. 61